Due to having the capacity of bending, flexible circuit boards can be applied to some fields where the circuit board will be bent. By using of a flexible circuit board, a LED flexible strip light can generate a line source with a elongated shape when electrified, so the flexible circuit boards can be widely applied to decoration and illumination in various situations, such as building, signboard, showcase and so on.
In traditional flexible circuit boards, a plurality of LEDs are welded on a soft circuit board with a elongated plate shape to form a LED strip source, and the periphery of the LED strip source is covered with an insulation layer, such that a line source with a elongated shape can be generated when electrified. The soft circuit board includes a conductive copper foil and an insulating film, and generally has a single-layer or multilayer structure, where the conductive copper foil and insulating film of each layer are independent of each other and stacked together, and the conductive copper foil can be divided into connection line and power wire. The LED flexible strip light has a high requirement on its width that the smaller the width is, the more flexible the LED flexible strip light is and the simpler the installation or the modeling is. However, in traditional soft circuit boards, the connection line and the power wire are generally positioned on a same plane, in this way, the width is large. In other cases, the connection line and the power wire may be positioned on different planes to reduce the width, but this structure has numerous deficiencies in production, such as too many planes to be stacked, complex process with more steps, much trouble to align the planes, low yield and so on.